Comparative studies on absorption patterns of the drug after intrarectal administration of 5-FU emulsion and 5-FU solution.

Intrarectal administration of 5-fluorouracil (5-FU) emulsion was compared experimentally with that of 5-FU solution as to the degree of absorption and tissue distribution. For the 5-FU levels in the rectal wall, the levels in the emulsion group remained at high levels during the 6 hour period after administration while the levels in the solution group decreased rapidly. For the 5-FU levels in the lymph nodes, those in the emulsion group were significantly higher (more than four times) and remained at relatively high levels for a longer period than those in the solution group. In the thoracic lymph, 5-FU levels in the emulsion group remained more than two times higher throughout the experimental period. The results suggest tha preoperative intrarectal administration of 5-FU emulsion may be effective as an adjunct to surgery for rectal cancer with lymph node metastasis, because of the long duration of high concentration resulting in the rectal lymphatics and rectal wall.